docs: Add note on Predicate

dangotbanned · dangotbanned · commit 841e88799def · 2024-10-30T16:13:27.000Z
Remember discovering this during (#3427), but hadn't documented
diff --git a/altair/vegalite/v5/api.py b/altair/vegalite/v5/api.py
@@ -538,6 +538,8 @@ def check_fields_and_encodings(parameter: Parameter, field_name: str) -> bool:
 -----
 - Quite similar to ``_PredicateType``
 - Probably some redundant typing, that can be reduced
+    - ``Predicate`` derives ``PredicateComposition``
+        - Includes all ``(Logical|Field|Parameter)...Predicate``
 """
 
 _ComposablePredicateType: TypeAlias = Union[
